It is quite old to provide a boat hull with a central tunnel and such a boat is commonly called a tunnel hull boat. It is furthermore old to provide a center rib extending down through this hull to give an added planing surface. The difficulty with such prior boats, however, has been that there has been an excessive tendency for the bow to rise at high speeds. A more pleasant effect is obtained when the stern also tends to rise somewhat so that the angle of inclination of the boat at high speeds is not excessive. Furthermore, in many boats of the tunnel hull type, there is a tendency for the boat to be appreciably affected by tail or head winds. Where there is a head wind, the bow tends to rise excessively. Where there is a tail wind, the bow does not rise as much as might be desired. In fact, the stern actually tends to be raised, thereby decreasing the speed of the boat.